1. Field of the Present Invention
The present disclosure relates to etching methods.
2. Description of the Related Art
An etching method is proposed, in which an antireflection film is processed through etching according to a pattern of a resist film, and the antireflection film and the resist film obtained through the etching process are used as a mask to perform an etching process on an object film that is disposed under the antireflection film, by performing plasma processing (e.g., Japanese Unexamined Patent Application Publication No. 2009-164626).
However, in a case where the antireflection film includes silicon and the resist film is ArF resist film, etc., an selective ratio of the antireflection film with respect to the resist film is low (e.g., 1-2). In a case where the selective ratio is low to disturb selective etching of the antireflection film with respect to the resist film, the resist film is also etched during the etching process of the antireflection film, and the resist film may be disappeared. Consequently, the object film under the antireflection film may be difficult to be etched, and the object film may not be vertically etched.
In particular, a selective ratio between an EUV resist film and the antireflection film is lower than the selective ratio between the ArF resist film and the antireflection film, where the EUV resist film is formed by using Extreme Ultra Violet (EUV) whose wavelength is 13-14 nm. Therefore, in a case where the EUV resist film is used as the mask, the etching process on the object film may become more difficult.
[Patent Document 1]: Japanese Laid-open Patent Publication No. 2009-164626
[Patent Document 2]: Japanese Laid-open Patent Publication No. 2011-134896